RAM 320XL is a external plug and play 320kB memory expansion card for 600XL and 800XL machines. Additionally there is a possibility to disable internal memory and remap it onto card (switchable via jumper), thus one can "fix" many failing XLs without even looking inside. Also, an unexpanded 16kB 600XLs can be upgraded to 320XL without any additional work.   RAM 320XL uses banking via bits 2,3,5,6 and 4 of PORTB. As you can see this is compatible with "Atari magazine" expansion rather than